The present invention relates to wheel alignment adjustment devices for automotive vehicles.
Misalignment of vehicle wheels may be caused by road shocks and the like or by improper wheel alignment, either at the factory or at the time new wheel assemblies or tires are installed. Improper wheel alignment may cause unnecessary tire wear and may also create vehicle handling problems.
Wheel alignment parameters include castor, camber and toe. Castor is the amount of forward or rearward angular displacement between a laterally extending vertical plane and a lateral plane which passes through upper and lower ball joint attachment portions of a steering knuckle. Castor angle effects vehicle steering. Camber refers to the amount of inward or outward tilt of the central plane of a wheel from a vertical plane (when the associated vehicle is resting on a level surface). A proper camber angle centers the vehicle load at the region where the tire contacts the road surface. Toe is the difference in the distance between the leading edges of a pair of oppositely positioned wheels (i.e. the front wheels or the rear wheels) and the distance between the trailing edges of that pair of wheels. Improper toe causes excessive tire wear and may cause a vehicle to wander or shimmy.
Some vehicles include apparatus in the vehicle suspension system which enable adjustment of wheel alignment parameters. However many vehicles are not equipped with such alignment adjustment apparatus or are equipped with apparatus which enable only limited adjustment of alignment parameters. As a result, many after-market kits have been introduced for sale to alignment shops for correction of vehicle alignment problems. Such kits generally include one or more items which are adapted to produce a displacement of one component of a wheel suspension assembly with respect to another component to produce a change in one or more alignment parameters.
U.S. Pat. No. 4,921,271 of Jimmy D. Berry and Robert M. Allman, which is hereby specifically incorporated by reference for all that it contains, discloses a bushing assembly for adjusting at least one wheel alignment parameter.
U.S. Pat. No. 4,616,845 (Re. 33,179) of Craig R. Pettibone and U.S. Pat. Nos. 4,695,073, 4,706,987, and 4,733,884 of Craig R. Pettibone and Jimmy D. Berry, all of which are hereby specifically incorporated by reference for all that is disclosed therein, describe several different cam-type alignment adjustment apparatus. U.S. Pat. No. Re. 33,179 discloses a toe adjustment assembly for adjusting the toe in the rear wheels of a vehicle having an independent rear suspension including: a cam device operatively associated with a lateral control arm, a slot provided in fixed relationship with the vehicle frame, and cam engaging surfaces associated with the slot. When the cam device is rotated, it coacts with the cam engaging surfaces to cause relative lateral shifting of a shaft portion of the cam device. This lateral shifting of the cam device shaft portion causes lateral shifting of the associated control arm and thus toe adjustment of an associated wheel.
In some suspension systems, the suspension components are positioned in such close relationship with other vehicle structure that there is insufficient clearance for use of a rotatable cam-type device for adjusting wheel alignment.
U.S. Pat. No. 4,863,187 of William P. Artz, which is hereby incorporated by reference for all that it contains, discloses a bolt restraining plate having a flange portion adapted to engage a strut flange peripheral edge for preventing lateral movement of the plate. The plate has a main body portion having a plurality of spaced apart holes therein adapted to receive a bolt therethrough for providing a different camber setting associated with each hole.
A problem with multiple separated bore plate devices such as described in the Artz patent is that each such plate provides relatively few different alignment settings and the increment of adjustment between such settings is relatively large.
Another problem with the use of alignment adjustment apparatus such as disclosed in the above discussed Pettibone and Artz patents is that it is necessary for a person installing the adjustment apparatus to modify existing suspension components of the vehicle rather than simply replacing existing suspension components with other apparatus components.